That looks like a Leech & Rigdon somebody adapted a Colt trigger guard to.
I like your emoticon! Based upon our previous conversations here, I am sure you know that it was originally a 2014 [CM] "tail" Pietta, and it has a Pietta G&G part octagon/part round barrel, the G&G plain cylinder. The SB TG was ordered from Taylor's back in the day, and it was the last one they had back then to fit the that grip profile. Everything after 2014 had a different grip profile and, thus, different parts as you know.
To my knowledge, Pietta never produced a Leech and Rigdon. I have one but it can only be made by swapping barrel, cylinder, and frame with other pistols, all Pietta.
I am that "somebody".
I still wish that Sam Colt had produced a pistol like that, but alas. It is still my favorite "fantasy" 1851 Navy .36.
Have a good evening, Hawg!
Jim